OFFSHORE VESSEL AND METHOD OF OPERATION OF SUCH AN OFFSHORE VESSEL

摘要

The present invention relates to an offshore vessel capable of installing and removing a subsea well control device and a riser string, the vessel comprising a hoisting device comprising a travelling block for connecting a load, which travelling block is displaceable along a firing line which extends through a moonpool and a heave compensation system. The vessel further comprises a working deck supported by the hull of the vessel which covers at least a portion of the moonpool to allow the assembly of a riser string, wherein said working deck is provided with a riser string suspension device that allows to suspend a top end of a string of risers. According to the invention, a heave compensation connection system is provided, which is adapted to connect the working deck to the travelling block, such that the hoisting device can move the working deck when the working deck is connected to the travelling block between a lowered riser assembly position allowing the assembly of a riser string, and in which the working deck is supported by the hull, and a raised heave compensated position, in which the working deck is connected to the travelling block, and wherein the working deck is heave compensated.